1. Field of the Invention
This novel invention is related to mechanical improvements in adjustable height non-inclinable worktables used to support large heavy work objects during a process involving constructing, carving, sculpturing, and/or manufacturing.
2. Description of Prior Art
In 1874 Semmendinger was issued U.S. Pat. No. 149,255 for an improvement in camera stands. A camera stand platform was made readily adjustable to a particular height using a load-bearing lever with a roller at the platform support end connected to a manual pawl detent and ratchet assembly.
Morey et al. received U.S. Pat. No. 1,650,293 on Nov. 22, 1927 entitled xe2x80x9cHospital Furniturexe2x80x9d. The Morey et al. invention of the prior art relates to improvements in hospital furniture, and has for its primary object the provision of a bed side table, particularly adapted for use in hospitals, with which is combined an adjustable and collapsible shelf structure, of which the latter is of such form and mounting that when not in use the same may occupy a folded or collapsed position lying parallel and adjacent to one side of the table, and when in an active position may be extended so as to provide a support permitting the placing of articles, such as food trays and the like, thereon.
Another aspect of the prior art invention resides in the provision of a hospital table with which is combined a foldable shelf structure, and wherein the supporting means for the shelf structure includes a non-rotatable vertical standard slidably supported within fixed guides carried by the side of the table, and wherein the standard is provided with a plurality of ratchet teeth cooperative with a pivoted locking detent which serves to maintain the standard locked automatically in any of its elevated positions of adjustment, so that the shelf or ledge carried in connection with the standard may be positioned at any desired elevation necessary to suit the convenience of the patient, and to adapt the shelf structure either to project over the bed of a reclining patient, or to permit the lowering of the same for use when the patient is occupying a chair or to maintain the shelf in any desired horizontal plane of adjustment.
A further prior art aspect resides in the provision of a foot operated releasing means by which the detent may be removed from engagement with the teeth of the shelf supporting standard so as to allow the latter to be lowered to assume a folded or inactive position.
Another prior art aspect is providing the upper end of the standard with a bifurcated head to which is pivotally connected one end of the supporting shelf, in order that when the shelf is lowered the same will lie closely adjacent and parallel to the side of the table upon which it is mounted and when raised the shelf will be swung to assume a position perpendicular to the table, novel locking and releasing means being provided for maintaining the shelf in its extended or active position where the shelf lies in a horizontal plane substantially at right angles to the table.
Other aspects of the Morey et al. invention reside in the provision of a table of a character wherein the shelf structure may be raised, lowered and adjusted with convenience and facility, and wherein the locking mechanism is of a positive and automatic character, devoid of set screws and the like to the end of assuring the retention of the shelf structure in any desired position of adjustment.
Noteworthy of the applicant""s novel invention is that the Morey et al. invention teaches away from any adaptation of its mechanism to a table top which is so heavy and massive compared to the mass of the standard that support of same in a horizontal position by a single standard cannot be achieved due to the center of gravity of the combined structure extending so much away from the standard as to cause it to tilt and fall over.
Likewise, Hall""s U.S. Pat. No. 1,687,128, which issued on Oct. 9, 1928 for a combination stool, chair, and table discloses a horizontal surface supported with one (central) adjustable vertical standard with the surface area of the horizontal surface being variable. A cantilevered tray supported on one edge wherein the elevating and actuating is done with one foot is suggested and disclosed in the bedside table patented by Walter on Apr. 28, 1931 in U.S. Pat. No. 1,802,362. Walter""s tray is not adapted for the support of substantial weight where the center of gravity of the table is such that it would readily tilt over.
On Nov. 22, 1932 Steidl received U.S. Pat. No. 1,888,478 for a combination table. Steidl, to enable easy adjustment of the table top and standard, counterbalanced it with a spring that he located inside a hollowed out standard, which centrally supported the top. For securing the table at various vertical heights, Steidl used a pawl and ratchet connection between the standard and a base. The ratchet was formed in or carried by the side of the standard and consisted of a set of upwardly faced pointed ratchet saw teeth. The saw teeth have at their supporting base surface abruptly shouldered seats on which the pawl rests. The pawl is a spring strip attached to the standard with the upper engaging end of the strip being the pawl in the form of a downwardly facing tooth or lug for engaging with the upwardly facing base of the ratchet teeth. The pawl is adapted with both engaging teeth and locking lugs in one unified structure and is utilized on only one vertical support surface of the standard.
On Jan. 19, 1943 U.S. Pat. No. 2,308,714 was granted to Ralston for an adjustable chair. It is noteworthy here because of its two vertical spaced apart support standards each of which employs a pawl and ratchet mechanism linked together via a single rod and lever mechanism for lowering and raising the chair using a pair of spring connected pawls for alternately engaging opposing rows of ratchets at each standard supporting the chair.
On Jul. 4, 1944 Parham was granted U.S. Pat. No. 2,353,064 for a beauty parlor stand wherein the improvement consisted of an adjustable single pedestal table top whereby implements placed thereon are all moved in closer proximity to a patron to save operator time.
On Dec. 19, 1967 U.S. Pat. No. 3,358,620 was granted to Italian inventor P. Parigi for a single tilted standard supporting a ratcheted and spring rotatable loaded worktable adapted as a drawing board.
It is a main object of the present invention to provide a heavy duty workbench capable of supporting work several times its weight at selected heights and further capable of moving and adjusting the work surface of the workbench up or down in small equal increments using a foot actuator improved with an interconnecting spring structure to avoid accidental disengagement.
It is another object of the present invention to provide a workbench having a height adjustable work surface using at least two manual and independent height adjustable standards.
It is yet another object of the present invention to provide a workbench with a height adjustable work surface, which can be tilted at both ends.
It is still another object of the present invention to provide a workbench wherein each standard is made of a pair of nesting inner and outer frames which together support one end of a workbench.
It is an object of the invention to provide a workbench wherein an inner support frame is locked at variably selected heights using a rounded pawl that disengageably engages one of a mating set of rounded ratchets.
It is another object of the invention to provide an adjustable height workbench top which is actuated using a foot pedal to generate a rotation of a rod, the rod being attached to the top and oriented parallel to the top, the rod acting as a pawl wherein the rod dually and simultaneously engages and/or disengages from a mating rounded ratchet arrayed in a vertical set of ratchets forming a part of two supporting standards.
One problem with the workbench structures of the prior art is that a structurally rigid heavy duty bench with an adjustable height top adapted to support several times the weight of the bench wherein the top is dually engaged by a single pawl-like structure has been heretofore unavailable. The pawl and ratchet mechanisms rely on individual pawls in each standard. These separated pawls do not structurally brace the workbench from one side to the other or provide integral support, relying instead on the top itself and separate bracing structures connected between the standards.
In the novel invention there is a vertical set of rounded ratchet slots or apertures which are engaged by a rod-like structure which extends from one edge of a standard to the other edge and which simultaneously engages the ratchet slots at the same height on each edge of the standard. In addition, a novel safety mechanism was discovered, designed and integrated into the workbench. This safety mechanism is a combination of a tension spring connected between a chain and a foot actuator pedal. It was discovered that this spring prevents accidental release of the rod by absorbing unintentional minor force applied to the pedal. Early prototypes would sometimes be inadvertently disengaged. Thus, the safety mechanism was incorporated into the novel workbench to prevent accidental disengagement from the supporting ratchet. Further, it was discovered that the rod-like structure (pawl) provides the best structural rigidity for the bench when rotated into the ratchet slots at an angle between less than 45 degrees and greater than about 10 degrees. Moreover, it was also discovered that when the rod-like pawl is combined with the mating round ratchet slots, wear is lessened compared to angulated ratchet slots or where a ledge or flat surface is formed on the rod as a point of engagement contact.
The rigidity of the bench and each standard is also improved by means of a novel locking action. This locking action or mechanism is a shim extension attached to a brace used at each side of the standard between an inner ratchet frame attached to the top of the bench and an outer frame, which rests on the floor. The shim extends between the back of the inner frame and the inner surface of the outer frame and presses and locks the ratchets on the inner frame against the ratchet engaging rod at each side of the inner frame. The angle formed by the line connecting the engaging rod axis and the rotating rod axis and horizontal is between about 10 degrees and 45 degrees.